Medical devices

ABSTRACT

Described are medical devices including expandable tubular bodies configured to be implanted into a lumen, wherein the outer surface of the expandable tubular bodies are coupled to a polymer(s).

RELATED APPLICATION

This application is a divisional of U.S. Pat. Application No.16/589,816, filed Oct. 1, 2019, which claims the priority of U.S.Provisional Pat. Application No. 62/739,633, filed Oct. 1, 2018, theentire content of which is incorporated herein by reference.

FIELD

Described herein are medical devices, including stents and flowdiverters, with covalently bonded polymer coatings that can reducethrombogenicity. Methods of making and using the medical devices arealso described.

SUMMARY

Described herein are medical device coatings. The device coatings can beused for any medical devices that may come into contact with tissueand/or blood. In some embodiments, the coatings can prevent or reducethrombus formation around a device when compared to an uncoated device.

Expandable, tubular bodies, including stents and flow diverters, arewidely used in the medical field to treat a variety of vascularconditions, including stenosis and dilatation or weakening of arterialwalls (i.e., aneurysm). For the treatment of stenosis, a stent isinserted into the blockage of the vessel and deployed. The stentbuttresses the blockage out of the lumen of the vessel, restoring bloodflow. For the treatment of an intracranial aneurysm, a stent may bedeployed across the neck of the aneurysm to provide support forsubsequent coiling of the aneurysm. Alternatively, a flow diverter maybe deployed across the neck of the aneurysm to reduce or eliminate theexposure of the aneurysm wall to blood flow.

While stents and flow diverters are widely used to successfully treatvarious vascular conditions, they are not without limitations. One suchlimitation is the requirement of anti-platelet therapy to preventthrombosis of the stent. Currently, dual antiplatelet therapy is thestandard of care. Low dose aspirin is recommended indefinitely. A P2Y12inhibitor (i.e., clopidogrel, prasugrel, ticagrelor, or cangrelor) isrecommended for up to 12 months post-procedure. While dual antiplatelettherapy is effective for maintaining the lumen of the stented vessel,bleeding (i.e., gastrointestinal or intracranial) complications canarise as well as other complications (e.g., stent induced thrombosis).While not frequent, these complications are associated with morbidityand mortality. As a result, efforts to reduce or eliminate dualantiplatelet therapy are being performed.

One such coating to reduce the thrombogenicity of stents isphosphorylcholine. In such an embodiment, a cobalt-chrome braided flowdiverter is covalently coupled with phosphorylcholine in effort toreduce thrombogenicity. A reduction in thrombogenicity of the coatedflow diverters compared to the uncoated flow diverters using thethrombogram test can be seen.

Another coating to potentially reduce the thrombogenicity of stents isheparin. In such an embodiment, a heparin coating is dip-coated orspray-coated over a stent in effort to reduce thrombogenicity. However,effects of the heparin coating in reducing thrombogenicity are notknown.

Anti-thrombotic coatings can be performed on tubular, expandable devicesas well as on a wide range of blood contacting medical devices,including tubing, catheters, cardiopulmonary bypass, and bloodoxygenators. For example, a polymeric coating comprisingpoly(methoxyethyl acrylate) has been developed for the coating of bloodgas oxygenators. This polymer is coated on every surface of theperfusion circuit to reduce thrombogenicity. However, this polymer issimply adsorbed to the surface and is suitable only for equipment thatwill be used for a short period of time.

Many other molecules have been evaluated for the coating of stents, flowdiverters, and other blood contacting medical devices. However, asatisfactory, durable coating has not been found.

Described herein are tubular, expandable devices. These devices can beconfigured to be implanted in the vasculature or other body lumen. Themedical device surface is coupled to an activated copolymer that canreduce the thrombogenicity of the tubular, expandable device. In someembodiments, the coupling is through a covalent linkage.

In one embodiment, the tubular, expandable devices include of aplurality of braided filaments woven into a configuration to beimplanted into a vessel. The braided filaments can be metallic. Themetallic composition can include gold, silver, copper, steel, aluminum,titanium, cobalt, chromium, platinum, nickel, combinations thereof,alloys thereof such as, but not limited to nitinol (nickel-titanium),cobalt-nickel, cobalt-chromium, platinum-tungsten, and combinationsthereof. The braided filaments can by polymeric. The polymeric braidedfilaments can comprise hydroxyl groups, e.g., on a surface of thefilaments.

In another embodiment, the tubular, expandable devices can include apolymeric tube laser cut into a configuration to be implanted into avessel. The polymeric tube may include hydroxyl groups, e.g., on asurface of the polymeric tube.

In another embodiment, the tubular, expandable devices can include ametallic tube laser cut into a configuration to be implanted into avessel. The metallic tube may include gold, silver, copper, steel,aluminum, titanium, cobalt, chromium, platinum, nickel, combinationsthereof, alloys thereof such as, but not limited to nitinol(nickel-titanium), cobalt-nickel, cobalt-chromium, platinum-tungsten,and combinations thereof.

In one embodiment, the activated copolymer can be prepared bycopolymerizing a first monomer, e.g., an alkoxyalkylacrylate or aderivative thereof, with a second monomer, e.g., a silane containingmonomer.

In one embodiment, the first monomer is of Formula (I):

wherein

-   R¹ is H or -C₁₋₄ alkyl,

-   R² is -C₁₋₄ alkylene, and

-   R³ is -C₁₋₄ alkyl;

-   or the first monomer is of Formula (II):

-   

In some embodiments, the first monomer is of Formula (I). In someembodiments, the first monomer is of Formula (II).

In some embodiments, R¹ is H, methyl, ethyl, propyl, or butyl. In someembodiments, R¹ is H or methyl.

In some embodiments, R² is methylene, ethylene, propylene, or butylene.In some embodiments, R² is methylene or ethylene.

In some embodiments, R³ is methyl, ethyl, propyl, or butyl. In someembodiments, R³ is methyl.

In some embodiments, R¹ is methyl and R³ is methyl.

In one embodiment, the first monomer is methoxyethyl acrylate (e.g.,2-methoxyethyl acrylate) or methoxyethyl methacrylate (e.g.,2-methoxyethyl methacrylate).

In one embodiment the second monomer comprises 1) a polymerizable sitesuch as an acrylate, methacrylate, acrylamide, or a combination thereof,and 2) a silane such as a monoalkoxy silane, a dialkoxy silane, atrialkoxy silane, or a combination thereof.

In one embodiment, the second monomer is of Formula (III):

wherein

-   R⁴ is H or -C₁₋₄ alkyl,-   R⁵ is -C₁₋₄ alkylene,-   R⁶ is -O-(C₁₋₄ alkyl),-   R⁷ is -C₁₋₄ alkyl or -O-(C₁₋₄ alkyl), and-   R⁸ is -C₁₋₄ alkyl or -O-(C₁₋₄ alkyl).

In some embodiments, R⁴ is H or —CH₃. In some embodiments, R³ is —CH₃.In some embodiments, R⁴ is —CH₃ and R⁶ is -OCH₃.

In some embodiments, R⁵ is methylene, ethylene, propylene, or butylene.

In some embodiments, R⁶ is —O—methyl, —O—ethyl, —O—propyl, or —O—butyl.

In some embodiments, R⁷ is methyl, ethyl, propyl, butyl, —O—methyl,—O—ethyl, —O—propyl, or —O—butyl.

In some embodiments, R⁸ is methyl, ethyl, propyl, butyl, —O—methyl,—O—ethyl, —O—propyl, or —O—butyl.

In some embodiments, R⁶ is —O—methyl, —O—ethyl, —O—propyl, or —O—butyl,R⁷ is methyl, ethyl, propyl, or butyl, and R⁸ is methyl, ethyl, propyl,or butyl.

In some embodiments, R⁶ is —O—methyl, —O—ethyl, —O—propyl, or —O—butyl,R⁷ is —O—methyl, —O—ethyl, —O—propyl, or —O—butyl, and R⁸ is methyl,ethyl, propyl, or butyl.

In some embodiments, R⁶ is —O—methyl, —O—ethyl, —O—propyl, or —O—butyl,R⁷ is —O—methyl, —O—ethyl, —O—propyl, or —O—butyl, and R⁸ is —O—methyl,—O—ethyl, —O—propyl, or -O-butyl.

In one embodiment, the second monomer is(3-acryloxypropyl)dimethylmethoxysilane,(3-acryloxypropyl)methyldiethoxysilane,(3-acryloxypropyl)methyldimethoxysilane,(3-acryloxypropyl)trimethoxysilane,(3-methacrylamidopropyl)trimethoxysilane,(methacryloxymethyl)dimethylethoxysilane,(methacryloxymethyl)methyldimethoxysilane,(methacryloxymethyl)methyldiethoxysilane,3-acrylamidopropyltrimethoxysilane, acryloxymethyltrimethoxysilane,methacryloxymethyltriethoxysilane, methacryloxymethyltrimethoxysilane,methacryloxypropyldimethylethoxysilane,methacryloxypropyldimethylmethoxysilane,methacryloxypropylmethyldiethoxysilane,methacryloxypropylmethyldimethoxysilane,methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane,or a combination thereof.

In some embodiments the activated copolymer can be prepared bycopolymerizing one or more first monomers provided herein with one ormore second monomers provided herein.

In one embodiment, the first monomer is of Formula (I) and the secondmonomer is of Formula (III). In one embodiment, the first monomer is ofFormula (II) and the second monomer is of Formula (III).

In one embodiment, the first monomer is methoxyethyl acrylate (e.g.,2-methoxyethyl acrylate) or methoxyethyl methacrylate (e.g.,2-methoxyethyl methacrylate), or a combination thereof, and the secondmonomer is (3-acryloxypropyl)dimethylmethoxysilane,(3-acryloxypropyl)methyldiethoxysilane,(3-acryloxypropyl)methyldimethoxysilane,(3-acryloxypropyl)trimethoxysilane,(3-methacrylamidopropyltrimethoxysilane,(methacryloxymethyl)dimethylethoxysilane,(methacryloxymethyl)methyldimethoxysilane,(methacryloxymethyl)methyldiethoxysilane,3-acrylamidopropyltrimethoxysilane, acryloxymethyltrimethoxysilane,methacryloxymethyltriethoxysilane, methacryloxymethyltrimethoxysilane,methacryloxypropyldimethylethoxysilane,methacryloxypropyldimethylmethoxysilane,methacryloxypropylmethyldiethoxysilane,methacryloxypropylmethyldimethoxysilane,methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane,or a combination thereof.

In some embodiments, the ratio of the first monomer to the secondmonomer is about 50:50 to about 99:1. In some embodiments, the ratio ofthe second monomer to the first monomer is about 50:50 to about 99:1.

Methods of coating an implantable medical device are also described. Themethods can include activating a surface of the implantable medicaldevice by hydroxylation, and coupling an activated copolymer formed froma first monomer, e.g., an alkoxyalkylacrylate or a derivative thereof,with a second monomer, e.g., a silane containing monomer to theactivated surface.

In some embodiments, the methods comprise hydroxylation of the surfaceusing oxygen plasma, water plasma, or hydrogen peroxide to generate anactivated surface. In some embodiments, the methods comprisehydroxylation of the surface using oxygen plasma to generate anactivated surface.

In some embodiments, the method further includes argon plasma treatmentafter hydroxylation.

DETAILED DESCRIPTION

The medical devices described herein may be any material or device thatcontacts blood flow, including oxygenators, artificial blood vessels,cardiopulmonary bypass machines, catheters, guidewires, stents, flowdiverters, venous filters, distal protection devices, tubing,stent-grafts, and the like. In some embodiments, the medical device is astent or flow diverter. In other embodiments, the medical device is abraided stent or flow diverter.

At least a portion of a medical device surface can be coated. In someembodiments, portions of a medical device may be masked using the hereindescribed coatings. In some embodiments, at least about 10 %, at leastabout 20 %, at least about 30 %, at least about 40 %, at least about 50%, at least about 60 %, at least about 70 %, at least about 80 %, atleast about 90 %, at least about 95 %, or at least about 95 % of themedical device surface can be coated.

The surfaces of the medical devices can be treated/coated to reducethrombogenicity. The medical devices can include a surface treatment toreduce thrombogenicity as well as methods for application of thecoatings to medical devices.

The substrate for the coating may be any suitable material, includingmetals, glass, polymers, ceramics, combinations thereof, and the like.In some embodiments, the substrate is a metal. While any metallicsurface may be used, suitable metals can include gold, silver, copper,steel, aluminum, titanium, cobalt, chromium, platinum, nickel, alloysthereof, and combinations thereof. Suitable alloys can include nitinol(nickel-titanium), cobalt-nickel, cobalt-chromium, andplatinum-tungsten. In one embodiment, the substrate is a combination ofnitinol and platinum-tungsten. In some embodiments, the substrate is apolymer. In some embodiments, the suitable material can be activated byhydroxylation.

A polymer of the reduced thrombogenicity coating can be prepared bypolymerization of two or more monomers, e.g., a first monomer and asecond monomer as provided herein.

In one embodiment, to prepare the polymer, the two or more monomers andan initiator are dissolved in a solvent. In general, any solvent thatdissolves the two or more monomers and the initiator can be used.Suitable solvents can include methanol/water, ethanol/water,isopropanol/water, dioxane/water, tetrahydrofuran/water,dimethylformamide/water, dimethylsulfoxide and/or water, andcombinations thereof. With carboxylic acid and hydroxyl containingmonomers, a wider range of solvents can be utilized, including toluene,xylene, dimethylsulfoxide, dioxane, THF, methanol, ethanol, and dimethylformamide.

Polymerization initiators can be used to start the polymerization of themonomers in the solution. The polymerization can be initiated byreduction-oxidation, radiation, heat, or any other method known in theart. Radiation cross-linking of the monomer solution can be achievedwith ultraviolet light or visible light with suitable initiators orionizing radiation (e.g. electron beam or gamma ray) without initiators.Polymerization can be achieved by application of heat, either byconventionally heating the solution using a heat source such as aheating well, or by application of infrared light to the monomersolution.

In some embodiments, an initiator may not be used.

In one embodiment, the polymerization initiator isazobisisobutyronitrile (AIBN) or a water soluble AIBN derivatives(2,2′-azobis(2- methylpropionamidine) dihydrochloride), or4,4′-azobis(4-cyanopentanoic acid). Other suitable initiators includeN,N,N′,N′-tetramethylethylenediamine, ammonium persulfate, benzoylperoxides, and combinations thereof, including azobisisobutyronitriles.Initiator concentrations can range from about 0.25 % to about 2 % w/w ofthe mass of the monomers in solution. The polymerization reaction can beperformed at elevated temperatures, such as in the range from about 65to about 85° C. After the polymerization is completed, the polymer canbe recovered by precipitation in a non-solvent and dried under vacuum.

In some embodiments, the polymers described herein can have a molecularweight of greater than about 10,000 g/mol, between about 10,000 g/moland about 200,000 g/mol, between about 8,000 g/mol and about 200,000g/mol, between about 100,000 g/mol and about 200,000 g/mol, betweenabout 50,000 g/mol and about 200,000 g/mol, between about 25,000 g/moland about 200,000 g/mol, between about 8,000 g/mol and about 100,000g/mol, between about 10,000 g/mol and about 100,000 g/mol, between about50,000 g/mol and about 100,000 g/mol, between about 75,000 g/mol andabout 100,000 g/mol, between about 75,000 g/mol and about 200,000 g/mol,about 10,000 g/mol, about 50,000 g/mol, about 100,000 g/mol, about150,000 g/mol, or about 200,000 g/mol.

In one embodiment, the polymer is applied to the substrate in severalsteps, each of which may or may not be optional. In some embodiments,the polymer is applied to the substrate in three steps. The necessity ofeach step is driven by the selection of the substrate.

Step 1 includes cleaning. To clean the substrate, it can be incubated inacetone, methanol, ethanol, isopropyl alcohol, water, or a combinationthereof under sonication. The duration of each washing step ranges fromabout 1 minute to about 20 minutes. The temperature of sonication canrange from about 18 to about 55° C. Following the conclusion of Step 1,the substrate moves to Step 2. In some embodiments, Step 2 immediatelyfollows Step 1.

In some embodiments, cleaning can optionally include cleaning withsoap/detergent and water.

Step 2 includes hydroxylation, a treatment to increase the number ofhydroxyl groups on the surface of the substrate. The surface to betreated may be hydroxylated using a number of different oxidizers,including acids, bases, peroxides, plasma treatment, and combinationsthereof.

Acids for treatment include hydrochloric acid, nitric acid, sulfuricacid, hydrofluoric acid, perchloric acid, and combinations thereof.Bases for treatment include sodium hydroxide, ammonium hydroxide, andcombinations thereof. Peroxides for treatment include hydrogen peroxide,t-butyl peroxide, and combinations thereof. In one embodiment, anoxidizer is hydrogen peroxide. The oxidizer used for hydroxylation maybe in concentration from about 1% to about 100%. The hydroxylationduration can range from about 0.25 hr to about 4 hr at temperaturesranging from about 18 to about 100° C. After hydroxylation, thesubstrate may be washed in acetone, methanol, ethanol, isopropylalcohol, water, or combination thereof, with or without sonication. Eachwash can range from about 1 minute to about 15 minutes in duration.Drying under vacuum may optionally follow washing. In one embodiment, ahydroxylation utilizes about 10% hydrogen peroxide at about 100° C. forabout 45 minutes followed by about 5 min sequential washes in water,ethanol, and acetone followed by drying under vacuum.

In another embodiment oxygen plasma is used for treatment. The substratecan be exposed to oxygen plasma in a plasma treatment machine. Plasmatreatment parameters can include oxygen flow, watts, pressure, and time.Oxygen flow can be from about 1 - 500 sccm, about 1 - 250 sccm, about1 - 120 sccm, about 100 - 500 sccm, about 100 - 200 sccm, about 100 -140 sccm, at least about 100 sccm, at least about 50 sccm, or less thanabout 500 sccm. Power can be from about 1 - 600 watts, about 1 - 500watts, about 1 - 400 watts, about 100 -600 watts, about 200 - 600 watts,about 400 - 600 watts, at least about 400 watts, at least about 500watts, or less than about 600 watts. Pressure can be from about 120 -2000 mTorr, about 200 - 2000 mTorr, about 200 - 1000 mTorr, about 300 -500 mTorr, about 300 - 2000 mTorr, at least about 200 mTorr, at leastabout 300 mTorr, or less than about 2000 mTorr. Time can be from about1 - 15 minutes, about 5 - 15 minutes, about 5 - 10 minutes, at leastabout 5 minutes, at least about 4 minutes, at least about 3 minutes, atleast about 2 minutes, or at least about 1 minute. In one embodiment theoxygen flow is about 120 sccm, the power is about 500 watts, thepressure is about 400 mTorr, and the time is about 5 minutes.

Following hydroxylation, the substrate may be optionally plasma treatedwith an argon plasma to clean the surface.

Plasma treatment parameters can include argon flow, watts, pressure, andtime. Argon flow can be from about 1 - 500 sccm, about 1 - 250 sccm,about 1 - 120 sccm, about 100 - 500 sccm, about 100 - 200 sccm, about100 - 140 sccm, at least about 100 sccm, at least about 50 sccm, or lessthan about 500 sccm. Power can be from about 1 - 500 watts, about 1 -400 watts, about 1 - 300 watts, about 100 - 500 watts, about 200 - 500watts, about 200 - 400 watts, at least about 100 watts, at least about200 watts, or less than about 500 watts. Pressure can be from about120 - 2000 mTorr, about 200 - 2000 mTorr, about 200 -1000 mTorr, about300 - 500 mTorr, about 300 - 2000 mTorr, at least about 200 mTorr, atleast about 300 mTorr, or less than about 2000 mTorr. Time can be fromabout 1 - 15 minutes, about 5 - 15 minutes, about 5 - 10 minutes, atleast about 5 minutes, at least about 4 minutes, at least about 3minutes, at least about 2 minutes, or at least about 1 minute. In oneembodiment the argon flow is about 365 sccm argon flow, the power isabout 300 watts, and the pressure is about 500 mTorr for about 10minutes.

Step 3 includes activated copolymer coupling, a treatment to covalentlycouple the activated copolymer to the substrate. Following plasmatreatment, the substrate can be placed in an activated copolymer(copolymer comprising a silane): solvent system in order to couple theactivated copolymer to the substrate. During this step, the functionalgroup imparted to the polymer from the second or more monomer can bereacted to the hydroxyl group imparted to the substrate viahydroxylation. In this step, the polymer can be dissolved in water,buffer, methanol, ethanol, isopropanol, butanol, dimethyl formamide,dimethyl sulfoxide, ethyl acetate, toluene, chloroform, dichloromethane,or a combination thereof. The solvent for this step can be 50% v/vethanol: 50% v/v citric buffer in water pH 7. The concentration of thepolymer in the solvent can range from about 0.5% to about 95% in thesolvent. In one embodiment, the concentration of the polymer in thesolvent is about 1%. The duration of the incubation ranges from about1-48 hrs (e.g., about 6 hrs to about 24 hrs) at a temperature range fromabout 18 to about 55° C. The coupling may optionally be performed withshaking at a rate from about 100 rpm to about 250 rpm. In oneembodiment, coupling conditions are incubation for about 18 hours atroom temperature with shaking at about 150 rpm.

After coupling, the substrate may be rinsed in ethanol, methanol,isopropanol, toluene, water, butanol, dimethyl formamide, dimethylsulfoxide, ethyl acetate, chloroform, dichloromethane, and combinationsthereof. In one embodiment, a rinse is ethanol. The copolymer layer maythen be cured at temperature ranging from about 30 to about 150° C. fora duration ranging from about 5 min to 60 min. Curing conditions can beabout 110° C. for about 30 min.

The polymer solution may be applied to the substrate by dip coating,spraying, brushing, or a combination thereof. In one embodiment, thesubstrate may be immersed in a an activated copolymer solution for about1 hour to about 48 hours. In one embodiment, the immersion duration isabout 18 hours. The incubation may be conducted at temperatures rangingfrom about 18 to about 100° C. In one embodiment, the temperature isroom temperature. The coupling reaction may optionally be performed withshaking at a rate from about 100 rpm to about 250 rpm. In oneembodiment, shaking conditions are about 150 rpm.

After the incubation, the substrate may optionally be rinsed ethanol,methanol, isopropanol, toluene, water, butanol, dimethyl formamide,dimethyl sulfoxide, ethyl acetate, chloroform, dichloromethane, andcombinations thereof. In one embodiment, rinsing is in 50% v/vethanol:50% v/v water. After rinsing, the substrate may be dried usingheat or vacuum. The substrate may be heated at temperatures ranging fromabout 40° C. to about 100° C., with or without vacuum. In someembodiments, drying conditions are 40° C. under vacuum. After drying,the substrate can be sterilized and packaged.

The coated devices can be sterilized without substantially degrading thecoating. After sterilization, at least about 50%, about 60%, about 70%,about 80%, about 90%, about 95% about 99% or about 100% of the coatingcan remain intact. In one embodiment, the sterilization method can beautoclaving, gamma irradiation, pressure sterilization, and/or steamsterilization.

The coatings described herein can prevent the growth of thrombin. Insome embodiments, the coatings can reduce the amount of wet thrombinformation by about 50% to about 90%, about 70% to about 90%, about 70%to about 100%, at least about 60%, or at least about 70%. In someembodiments, the coatings can reduce the amount of thrombin formation,when measured dry, by about 60% to about 95%, about 70% to about 95%,about 70% to about 100%, at least about 70%, at least about 80%.or atleast about 90%.

Example 1 Preparation of the Braided Medical Device for Hydroxylation

First, the braided medical device is pre-cleaned using sequentialincubations in acetone, ethanol, and water for 5 minutes each whilesonicating. The cleaned braided medical device is incubated in asolution of 10% hydrogen peroxide in water for 45 minutes at 100° C. andthen rinsed three times with water. The braided medical device iscleaned using sequential incubations in water, ethanol, and acetone for5 minutes each while sonicating. Finally, the braided medical device isdried under vacuum for 18 hours.

Example 2 Hydroxylation of the Braided Medical Device via Oxygen Plasma

First, the braided medical device is pre-cleaned using sequentialincubations in acetone, ethanol, and water for 5 minutes each whilesonicating. Then, the braided medical devices are transferred to avacuum oven and dried under reduced pressure at 40° C. for 30 min. Thedried braided medical devices are activated on an IoN 40 PlasmaProcessing System instrument, using the following parameters:

Flow (Oxygen) 120 +- 10 sccm Watts 500 watts Pressure 400 mTorr Time 5minutes

The activated braided medical devices are then stored in vials.

Example 3 Preparation of a Copolymer of a Monomer of Formula (I) and aMonomer of Formula (III)

To a mixture of 40 mL water and 40 mL methanol, 40 g of a monomer ofFormula (I), 4 g of a monomer of Formula (III), and 440 mg ofazobisisobutyronitrile are dissolved. Polymerization occurs over 20hours at 65° C. The copolymer is recovered by precipitation in a mixtureof isopropanol:hexanes (500 mL: 500 mL). The copolymer is re-dissolvedin 100 mL tetrahydrofuran and re-precipitated in a mixture ofisopropanol:hexanes (400 mL: 600 mL). The copolymer is re-dissolved in100 mL tetrahydrofuran and re-precipitated in a mixture ofisopropanol:hexanes (300 mL: 700 mL). The copolymer is redissolved in100 mL tetrahydrofuran and reprecipitated in a mixture ofisopropanol:hexanes (200 mL: 800 mL). Finally, the copolymer is stirredin 1 L of hexane for 1 hour and dried under vacuum.

Example 4 Preparation of the Coated, Braided Medical Device Using aCopolymer of a Monomer of Formula (I) and a Monomer of Formula (III)

The copolymer of Example 3 is dissolved in 50%/50% of ethanol/citricbuffer 7.0 pH (v/v) at a final concentration of 10 mg/mL. The braidedmedical device of Example 2 is placed into a vial containing thecopolymer solution and incubated for 18 hours at room temperature on theorbital shaker at 150 rpm. After incubation, the device is rinsed with50%/50% ethanol/ water and cured at 40° C. for 30 minutes under vacuum.

Example 5 Evaluation of the Coated, Braided Medical Device Using theChandler Loop Model

PVC tubing (4 mm inner diameter and 6 mm outer diameter, 54.86 cmlength) is measured and cut to fit on the cradle of the Chandler loopinstrument (Industriedesign, Neuffen, Germany). A single pre-weighedcoated, braided medical device (4.5 mm x 2 cm) is deployed into thetubing. Bovine blood is freshly collected from a local slaughterhouseand heparinized at 1U/mL. The activation clotting time (ACT) is adjustedto be between 150 and 250 seconds with protamine, if necessary. Thetubing is filled with blood and the tubing is sealed with a connector.The loop is fit onto a polycarbonate stabilization disk, which is thenfixed onto the Chandler Loop instrument. The loops are rotated for 2hours at a shear rate of 300 S⁻¹ at 37° C.

The assemblies are then taken out of the Chandler loop instrument andthe blood is drained into PTFE beakers. The ACT of the drained blood isdetermined. The tubing is thoroughly rinsed with PBS three times toremove any residual blood. The tubing is longitudinally cut with a razorblade and the braided medical device is retrieved and photographed. Thestent is weighed (wet weight) and then dried at 37° C. until the weightis constant (dry weight).

Example 6 Evaluation of the Coated, Braided Medical Device Using X-rayPhotoelectron Spectroscopy

The struts of the braided medical device are analyzed using x-rayphotoelectron spectroscopy to determine elemental composition.

Example 7 Evaluation of the Coated Medical Device Using Thrombogram

Thrombogram is performed on a Thrombinoscope instrument (ThrombinoscopeB.V., Maastricht, Netherlands) in accordance with the manual. On a96-well plate, the negative controls, test articles, and thrombincalibrator are arrayed with 9 replicates per group. Platelet-poor plasma(PPP, 240 µL) is added to all the wells and PPP-reagent (60 µL) is addedto the negative control and test articles. After the FluCa solution hasbeen added to the instrument, the start button is pressed and the 96well plate was inserted into the instrument, starting the 10 minuteincubation. At the conclusion of the incubation, the results areprocessed and reported.

Example 8 Evaluation of the Coated, Braided Medical Device Using BloodLoop

The Example 7 braided medical devices are packaged into a deliverysystem and sterilized with E-beam. PVC tubing inner-lined with X-coating(OD = 5/16″, ID = 3/16″, Terumo, Japan) is cut into 140 cm length. Thetubing is filled with saline and three identical devices are deployedinto the tubing. Saline is then replaced with ovine blood (heparinizedat 1 U/mL), and the ACT of the blood is between 150 to 250 seconds. Tobegin the test, the tubing is closed with tubing connector into a loopand loaded onto a peristaltic pump. While incubating the loop in aheating chamber, blood is circulated inside the loop at 273 s-1 for 2hours ± 30 min. At the end of the incubation, blood is drained from eachloop and the ACT is measured. The full length of the tubing is rinsedwith saline. The stent is cut out of the tubing, weighed (wet weight),and then dried at 37° C. until the weight is constant (dry weight).

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe specification and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques. Notwithstanding that the numerical ranges and parameterssetting forth the broad scope of the invention are approximations, thenumerical values set forth in the specific examples are reported asprecisely as possible. Any numerical value, however, inherently containscertain errors necessarily resulting from the standard deviation foundin their respective testing measurements.

The terms “a,” “an,” “the” and similar referents used in the context ofdescribing the invention (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.Recitation of ranges of values herein is merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range. Unless otherwise indicated herein, eachindividual value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention otherwise claimed. No languagein the specification should be construed as indicating any non-claimedelement essential to the practice of the invention.

As used herein, the term “alkoxyl” alone or in combination with otherterms means, unless otherwise stated, an alkyl group having thedesignated number of carbon atoms, as defined herein, connected to therest of the molecule via an oxygen atom.

As used herein, the term “alkyl” alone or in combination with otherterms means, unless otherwise stated, a straight or branched chainhydrocarbon having the number of carbon atoms designated (i.e., C₁₋₄means one to four carbon atoms) and includes straight or branched chainsubstituent groups.

Groupings of alternative elements or embodiments of the inventiondisclosed herein are not to be construed as limitations. Each groupmember may be referred to and claimed individually or in any combinationwith other members of the group or other elements found herein. It isanticipated that one or more members of a group may be included in, ordeleted from, a group for reasons of convenience and/or patentability.When any such inclusion or deletion occurs, the specification is deemedto contain the group as modified thus fulfilling the written descriptionof all Markush groups used in the appended claims.

Certain embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Ofcourse, variations on these described embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than specifically described herein. Accordingly,this invention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

Furthermore, numerous references have been made to patents and printedpublications throughout this specification. Each of the above-citedreferences and printed publications are individually incorporated hereinby reference in their entirety.

In closing, it is to be understood that the embodiments of the inventiondisclosed herein are illustrative of the principles of the presentinvention. Other modifications that may be employed are within the scopeof the invention. Thus, by way of example, but not of limitation,alternative configurations of the present invention may be utilized inaccordance with the teachings herein. Accordingly, the present inventionis not limited to that precisely as shown and described.

What is claimed is:
 1. A medical device, comprising an outer surfacecoupled to a polymer prepared from the free radical polymerization of:at least one first monomer selected from alkoxyalkylacrylates or(tetrahydrofuran-2-yl)methyl acrylate; and at least one second monomerselected from silane containing monomers.
 2. The medical device of claim1, wherein: the alkoxyalkylacrylate is of the formula:

wherein R¹ is H or —C₁₋₄ alkyl, R² is —C₁₋₄ alkylene, and R³ is —C₁₋₄alkyl.
 3. The medical device of claim 1, wherein the medical deviceincludes a metal that is a combination of nitinol and platinum-tungsten.4. The medical device of claim 1, wherein the polymer is covalentlycoupled to the outer surface.
 5. The medical device of claim 1, whereinthe polymer is prepared from the free radical polymerization of: A) atleast one first monomer selected from alkoxyalkylacrylates; and the atleast one second monomer selected from silane containing monomers; or B)(tetrahydrofuran-2-yl)methyl acrylate; and the at least one secondmonomer selected from silane containing monomers.
 6. (canceled)
 7. Themedical device of claim 2, wherein: R¹ is H or methyl; and R² ismethylene or ethylene.
 8. The medical device of claim 2, wherein: R¹ ismethyl; and R³ is methyl.
 9. The medical device of claim 1, wherein theat least one second monomer comprises: 1) an acrylate, a methacrylate,an acrylamide, or a combination thereof; and 2) a monoalkoxy silanemoiety, a dialkoxy silane moiety, a trialkoxy silane moiety, or acombination thereof.
 10. The medical device of claim 1, wherein: the atleast one first monomer is a methoxyethyl acrylate, a methoxyethylmethacrylate, or a combination thereof; and the at least one secondmonomer is (3-acryloxypropyl)dimethylmethoxysilane,(3-acryloxypropyl)methyldiethoxysilane,(3-acryloxypropyl)methyldimethoxysilane,(3-acryloxypropyl)trimethoxysilane,(3-methacrylamidopropyl)trimethoxysilane,(methacryloxymethyl)dimethylethoxysilane,(methacryloxymethyl)methyldimethoxysilane,(methacryloxymethyl)methyldiethoxysilane,3-acrylamidopropyltrimethoxysilane, acryloxymethyltrimethoxysilane,methacryloxymethyltriethoxysilane, methacryloxymethyltrimethoxysilane,methacryloxypropyldimethylethoxysilane,methacryloxypropyldimethylmethoxysilane,methacryloxypropylmethyldiethoxysilane,methacryloxypropylmethyldimethoxysilane,methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane,or a combination thereof.
 11. The medical device of claim 10, whereinthe at least one first monomer is 2-methoxyethyl acrylate,2-methoxyethyl methacrylate, or a combination thereof.
 12. The medicaldevice of claim 1, wherein the ratio of the at least one first monomerto the at least one second monomer is about 50:50 to about 99:1, or theratio of the at least one second monomer to the at least one firstmonomer is about 50:50 to about 99:1.
 13. The medical device of claim 1,wherein the at least one second monomer is(3-acryloxypropyl)dimethylmethoxysilane,(3-acryloxypropyl)methyldiethoxysilane,(3-acryloxypropyl)methyldimethoxysilane,(3-acryloxypropyl)trimethoxysilane,(3-methacrylamidopropyl)trimethoxysilane,(methacryloxymethyl)dimethylethoxysilane,(methacryloxymethyl)methyldimethoxysilane,(methacryloxymethyl)methyldiethoxysilane,3-acrylamidopropyltrimethoxysilane, acryloxymethyltrimethoxysilane,methacryloxymethyltriethoxysilane, methacryloxymethyltrimethoxysilane,methacryloxypropyldimethylethoxysilane,methacryloxypropyldimethylmethoxysilane,methacryloxypropylmethyldiethoxysilane,methacryloxypropylmethyldimethoxysilane,methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane,or a combination thereof.
 14. (canceled)
 15. The medical device of claim2, wherein the silane containing monomer is of the formula:

wherein R⁴ is H or —C₁₋₄ alkyl, R⁵ is —C₁₋₄ alkylene, R⁶ is —O-(C₁₋₄alkyl), R⁷ is —C₁₋₄ alkyl or —O-(C₁₋₄ alkyl), and R⁸ is —C₁₋₄ alkyl or—O-(C₁₋₄ alkyl).
 16. The medical device of claim 15, wherein: R³ is—CH₃; and R⁴ is H or —CH₃.
 17. The medical device of claim 15, wherein:R⁴ is —CH₃; and R⁶ is -OCH₃.
 18. The medical device of claim 15,wherein: R⁶ is —O—methyl, —O—ethyl, —O—propyl, or —O—butyl; R⁷ ismethyl, ethyl, propyl, or butyl; and R⁸ is methyl, ethyl, propyl, orbutyl.
 19. The medical device of claim 15, wherein: R⁶ is —O—methyl,—O—ethyl, —O—propyl, or —O—butyl; R⁷ is —O—methyl, —O—ethyl, —O—propyl,or —O—butyl; and R⁸ is methyl, ethyl, propyl, or butyl.
 20. The medicaldevice of claim 15, wherein: R⁶ is —O—methyl, —O—ethyl, —O—propyl, or—O—butyl; R⁷ is —O—methyl, —O—ethyl, —O—propyl, or —O—butyl; and R⁸ is—O—methyl, —O—ethyl, —O—propyl, or —O—butyl.
 21. The medical device ofclaim 1, wherein the medical device includes an expandable tubular bodyconfigured to be implanted into a blood vessel.
 22. The medical deviceof claim 21, wherein the expandable tubular body includes a metal.23-35. (canceled)